Summary

• Red blood cells and haemoglobin, the molecule inside them that makes them red, carry oxygen from the lungs around the body.
• To make haemoglobin, your body needs iron.
• A test for transferrin measures the amount of iron that can be transported in your blood.
• It can be used by itself, but it is most often ordered as part of a group of tests known as iron studies which includes other tests relating to your body's iron levels.
• Iron Studies collectively looks at how much iron is in your blood and body.
• Your medical team may request iron studies if you have symptoms of having too little or too much iron. 

What is iron and why do we need it?

Your body needs iron for daily activities, growth and development. It uses iron to make haemoglobin in red blood cells. Red blood cells carry oxygen through the bloodstream from the lungs and release it to where it is needed in the body. 

Our bodies cannot make iron. It must be absorbed from our diet or from supplements. The amount of iron we absorb is decided by our body's needs. We normally use just a little bit of iron each day and we don’t have a way of getting rid of excess iron. Instead, the body closely controls iron levels by regulating how much iron is absorbed from our food.

How iron is taken up and used

• Iron is absorbed from your food into the bloodstream through your small intestine. Once the iron enters the blood, it sticks to a protein called transferrin. Transferrin transports it to various tissues throughout the body.
• Iron is stored in a protein called ferritin. This is found all over your body but mainly in the liver. Ferritin releases iron as it is needed when your body detects low iron levels in your blood.  
• Entering the bloodstream, iron once again sticks to transferrin, and it travels to the bone marrow where new blood cells are made.
• Here it is taken up by newly forming red blood cells which have transferrin receptors on their surface.  Entering through the receptor it moves into the cell where the iron is separated from the transferrin.

Since red blood cells live for an average of about 120 days, the body needs a constant supply of iron to maintain haemoglobin levels. Dying red blood cells are recycled and old haemoglobin is broken down to rebuild iron supplies.

Why get tested?

When iron stores are low, transferrin levels increase, and when there is too much iron, transferrin levels decrease. Total iron binding capacity (TIBC) is an older test that is sometimes still used. TIBC and transferrin give the same information — the amount of iron capable of being transported in the blood.

Having the test

Sample.

Blood.

Any preparation?

None.

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of these tests.

It is not possible to accurately interpret transferrin or TIBC results without looking at other tests in the iron studies group.

High transferrin or TIBC

A high transferrin or TIBC may be due to iron deficiency.  When the body lacks iron it increases its ability to transport iron by stepping up transferrin production.

However, a high transferrin or TIBC may not be due to iron deficiency.  For example, transferrin levels increase during pregnancy.  Transferrin levels may also increase as a side effect of some medications.

For these reasons, your doctor will look at all the results in the iron studies profile to see if the overall pattern suggests iron deficiency or another cause.

Low transferrin or TIBC

The most common cause of a low transferrin is acute inflammation.  Transferrin production by the body decreases during a period of inflammation, such as after recent surgery, during an infection, or if you have an autoimmune condition.

A low transferrin is also seen if you have too much iron, called iron overload.  Other results in the iron studies profile such as a high ferritin and high transferrin saturation may also indicate iron overload.

Reference intervals

Your results will be compared to reference intervals (sometimes called a normal range). 

• Reference intervals are the range of results expected in most healthy people of the same age and sex. 
• Your results may be flagged high or low if they sit outside this range.
• Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. Blood test results must be interpreted with an understanding of your own particular symptoms and clinical situation.  For this reason, your results are best interpreted by your own doctor.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How will the results from this test change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.

Get further trustworthy health information and advice from healthdirect.